An image forming apparatus includes a process unit that forms a toner image on a transfer belt. The image forming apparatus includes, for example, a process unit for each color. The process unit causes charging of a photoconductive drum and irradiates the photoconductive drum with light corresponding to an image data (print data) for printing, thereby forming an electrostatic latent image (electrostatic latent image) on the photoconductive drum. The process unit causes a toner to adhere to the latent image formed on the photoconductive drum using the developing unit. A transfer device transfers the toner adhered to the latent image on the photoconductive drum to the transfer belt. The image forming apparatus transfers the toner image on the transfer belt to the printing medium, presses the printing medium against a fixing roller of a high temperature, and fixes the toner image formed on the printing medium.
The developing unit includes a developing sleeve, a doctor blade, and a developer container. The developing sleeve rotates in the developer container which contains a developer containing a toner and a carrier, thereby causing the toner to adhere to the photoconductive drum. The doctor blade is a member disposed at a predetermined distance from the developing sleeve. The doctor blade removes some of the developer adhered to the surface of the developing sleeve when the developing sleeve rotates. Thus, a layer of the developer having a thickness corresponding to the distance between the doctor blade and the developing sleeve is formed on the developing sleeve. In this way, the doctor blade adjusts the thickness of the layer of the developer formed on the developing sleeve.
By heat generated in the image forming apparatus, the developer may be often solidified after being melted in the developing unit. For example, the developer adhered to the doctor blade is solidified after being melted, and thus the solidified developer may stick to the doctor blade. When the developer sticks to the doctor blade, the thickness of the layer of the developer formed on the developing sleeve may not be stabilized, and image defects may occur.